diff --git a/src/applications/notification/client/PhabricatorNotificationServerRef.php b/src/applications/notification/client/PhabricatorNotificationServerRef.php
--- a/src/applications/notification/client/PhabricatorNotificationServerRef.php
+++ b/src/applications/notification/client/PhabricatorNotificationServerRef.php
@@ -144,7 +144,13 @@
   }
 
   public function getURI($to_path = null) {
-    $full_path = rtrim($this->getPath(), '/').'/'.ltrim($to_path, '/');
+    $full_path = '/';
+    if (phutil_nonempty_string($this->getPath())) {
+      $full_path = rtrim($this->getPath(), '/').$full_path;
+    }
+    if (phutil_nonempty_string($to_path)) {
+      $full_path = $full_path.ltrim($to_path, '/');
+    }
 
     $uri = id(new PhutilURI('http://'.$this->getHost()))
       ->setProtocol($this->getProtocol())